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Comment by johnsmith1840 | Hacker News Reader

The dams in california were built years ago for a smaller population and since then they've only removed them.

If we simply built like the people who first came to california did we would never have water shortages again.

Any water shortage is a 1:1 failure of the state to do the clear and obvious task needed.

Water policy isn't as simple as you might think. Dams aren't a magical fix, they cause a lot of issues (like crashing the salmon populations, etc.). They're expensive to build and maintain, and the water you store in a big reservoir doesn't magically stay in place - you lose a lot to evaporation and you lose a lot that ends up going into the groundwater system. A much bigger part of the problem is western water law, where water rights are assigned based on prior appropriation and are lost if they aren't exercised. That leads to a lot of bullshit, like people growing very water hungry crops (alfalfa, rice) in the middle of the desert.

The reason we don't build like the people who first came to California did isn't because we're stupid, it's because we've learned a lot of lessons the hard way. If you're interested in some of the history I'd recommend Cadillac Desert, which is about western water in general, but which focuses a lot on California (including the machinations that the movie China Town was based on).

A lot of stuff re: Salmon Populations is primarily around native groups wanting to continue their traditional life styles.

In the era of Trump/Republicans, I don't expect native issues to matter at all. "Drill baby drill" and all that.

So, actually, it is pretty simple if you're willing to finish the settler colonialist project that is our country.

You should really read the book mentioned in the post you're responding to.

Thanks for contributing these insights. Having worked with hydrologists for 15 years or so -- water is complicated, and people who say there are simple solutions generally do not know the domain.

A moment's reflection should make this clear. It's such a fundamental resource, touching everything we do. We just tend to take it for granted.

All the best sites were built on long ago. Dams require favorable geography. More can be built to squeeze out a bit more storage, but there are diminishing returns.

https://www.ppic.org/publication/dams-in-california/

Can I ask why you see this as a clearcut issue? Dams have environmental costs, upfront monetary costs, maintenance costs, and can't prevent drought if conditions persist for multiple years. Why are dams the best way to address drought?

At best dams let you draw down water based on average rainfall. They cost water via evaporation if you don’t have excess rainfall to store.

Thus removing dams was actually useful amid a 25 year drought.

If you look into the actual design capacity of our municipal water systems, many of them were designed for far larger populations. The EBMUD, for example, intentionally secured 325 million gallons per day in upstream capacity because that was 10x the needs of the service area in 1929. Implicitly they assumed that the service area would grow to 4 million people, but it never did, primarily because of zoning. Today EBMUD delivers only about 120 MGD. We could more than double the service area population without water issues.

dams have trade offs that they stop sediment outflows which can cause faster erosion. this is a big reason many california beaches have gone from mostly sandy to mostly rocky

Yeah, and with California's typical topography (relatively younger mountains), there's a lot of sediment at the ready than can fill dams and render them worse than useless -- i.e., costs money, loses capacity fast, alters river and coast.

E.g.: https://en.wikipedia.org/wiki/Matilija_Dam#History

> Almost immediately after construction, the dam began silting up. The dam traps about 30% of the total sediment in the Ventura River system, depriving ocean beaches of replenishing sediment. Initially, engineers had estimated it would take 39 years for the reservoir to fill with silt, but within a few years it was clear that the siltation rate was much faster than anticipated.

There are similar sites all over the state. If you happen to live in the LA area, the Devil's Gate Dam above Pasadena is another such (but originally built for flood control, not for storage).

It's just not as easy as GP comment imagines.

The new Sites Reservoir and capacity increase of the existing San Luis Reservoir are both expected to start construction this year. Several other recent proposals like the Pacheos Reservoir have been cancelled due to cost but it is not the case that California is doing nothing re: new water infrastructure.

Sites Reservoir isn't going to do a damned thing for municipal water systems in most of the state. You have to remember that there is not such a thing as a statewide municipal water policy. Every city or region has its own thing going on. The Sites capacity is dedicated to its investors, so depending on where you live it could be a helpful resource, or it could be irrelevant.

Investors? It's publicly funded.

It is funded by water districts, and they are the ones who get to use it.

This is my point. They know what to do but have trouble doing so.

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